1. Field of the Invention
The present invention relates generally to materials processing and more specifically to processes and apparati for extracting various metals from mineral ores.
2. Description of the Prior Art
The arts of metallurgy and metal working pre-date written history. Extraction, melting, and fabrication of items in bronze and iron has been an essential part of human civilization for several thousand years. The precious metals gold and silver have been known for thousands of years and have long provided bases for currency and materials for construction of decorative and useful items.
Recently, the precious metals, particularly gold, silver, and platinum, have achieved greatly increased value. These metals have increased in value not only due to their decorative value and scarcity but also due to the fact that they are of extreme use in medical processes and in the fabrication of electronic components. With the drastic increase of the value of these precious metals has come a concurrent increase in the interest in obtaining these metals from the environment.
Processes and devices for extracting precious metals, particularly gold and silver, from mineral ores have been known for thousands of years. Nearly all of these processes have involved the application of high amounts of heat to the ores such that the precious metals would melt and flow from the ores. In many cases, various chemicals or materials were added to the ores prior to heating.
One extraction method which has been known since the beginning of written history is the use of metallic lead (Pb) as an extraction material. Metallic lead has a particular affinity for various metals including, gold, silver, platinum, manganese, and lead itself. It was recognized early that the use of elemental lead could aid in the extraction of these metals from their ores. However, very little attention has been paid to the particular procedure for maximizing the extraction or to the devices to be utilized for such extraction. The use of metallic lead as a precious metal extracter through the centuries has consistently been crude and has resulted in relatively low yields. High yield process modifications have not been forthcoming.
Lead extraction processes have been rarely utilized in the metal processing industry in modern times. Modern extraction methods are designed for high volume flow processes to which lead extraction technology has not yet been effectively adapted. These industrial processes are usually not readily adaptable for use in low volume processes such as assaying.